Method of concentrating ores



June 6, 1939. A H, LEJA I 2,161,477

METHOD 0F CONCENTRATING ORES Filed Jan. 26, 1938 s sheets-sheet 1 F151. f 3 '"r I 5 l III-M III III ZIII III I FIG. 2.

flyzfed H Leja INVENTOR.

ATTORNEY.

June 6, 1939. A, H) LEJA METHOD OF GONGENTRATING ORES Filed Jan. 26, 1959 5 Sheets-Sheet 2 I CW IV ATTORNEY.

June 6, 1.939. A H LEJA -2,l61,477

METHOD OF CONCENTRATING ORES I Filed Jan. 26, 19:58 `s sheets-sheet :s

FIG. 4.

f 'el 5,@ 57) 1 4 l 57 by f 53 ,7' 53 .yrecl H Leja IN VENTOR.

ATTORNEY.

Patented June 6, 1939 PATENT ori-ICE METHOD 0F CON CENTRATING ORES Alfred H. Leia, Milwaukee, Wis., assignor to A. 0.v

Smith Corporation, Milwaukee, Wis., a

tion of New York Application January 26, 1938, Serial No. 188,931

5 Claims.

This invention relates to an improved method of classifying materials and particularly ores in which particles such as gold may be separated on the basis of their heavier specific gravities.

It has been customary in` concentrating ores to pass a pulp containing finely ground ore over a sluice box or riilie board by means of which the heavier particles are deposited along the riiiles while the lighter particles are washed away with the iluid. The principal objection to this process arises from the fact that the original deposit contains a large quantity of said and other lighter particles which are undesirable and which lower the degree of concentration attainable. In the use of rotary bowls equipped with riffles in which lconcentration is effected by centrifugal force, the same difficulties exist and are possibly of greater magnitude because the centrifugal force throwing the lighter particles into the riiile grooves is greater than gravity. Clogging of the riies is` the undesirable consequence.

It is an object of the present invention to provide a method-of concentrating ores making use of apparatus of the type before mentioned, but imparting to the ore deposited along the riiile surface a periodic agitation, effected by a corresponding periodic change of riiile volume, by means of displacement of the rimes, which in the case of the centrifugal bowl, may be either axial, angular or radial.

A further object of the invention is to provide a method of periodically changing the riiile volume by axial, angular and radial rime displacement during the process of concentration to cause the expulsion of lighter particles deposited in one set of rile grooves while retaining the heavier ones and collecting in adjacent grooves the heavier particles which are expelled from the first set of grooves until a saturation point for the collection of heavy particles is reached.

A still further Objectis to improve the concentration by passing the pulp along a riie surface and periodically imparting a movement to the base of the rile grooves to agitate the ore derotary type bowl provided with riilles which may be periodically vibrated as herein described; y Fig. 3 is a vertical longitudinal central section .of the preferred apparatus for embodying the invention, the rimes being shown in neutral position;

Fig. 4 is a plan vie'w ofthe apparatus shown in Fig. 3, a portion of the bowl being shown in section, and

Fig. 5 is an enlarged detail sectional view of the rimes in one extreme position of movement, the central portion being broken away.

Referring to Fig. l, the pulp containing ore to be classified is passed over the sluice box I in the direction of the arrow and the ore permitted to deposit in grooves 2 between rimes 3. The rime surface may be conveniently defined by an apron 4 of rubber or similar material drawn over a number of transverse riillle-forming bars 5 and 5'. Alternate bars 5' are movable relative to stationary bars 45`and are connected torods 6 arranged in the direction of pulp ow. By reciprocating the rods yat periodic intervals alternate grooves will be respectively widened and narrowed, and as a result ore deposited in a groove which is being narrowed will be expelled, while at the same time the next groove in the course of pulp flow will be widened to receive the` expelled ore as well as additional ore from the pulp stream. The tendency will be for the heavier particles to stay at the bottom of the groove, Iwhile the lighter, undesirable particles such as sand will be gradually worked out of the grooves by repeated reciprocation of the rimes, A higher grade of concentration ot heavier particles results from this process.

If the surface illustrated in Fig. 1 be rolled up to provide a sleeve, the same manner of operation may be applied to a bowl type of concentrator. In Fig. 2, a rillle sleeve 1 is drawn over a coil spring 8 placed inside a bowl 9. Pulp is fed through the center of the bowl I0 to the bottom, and when the bowl is rotated the pulp is forced upwardly over the riille surface and out the top of the bowl. By compressing the spring 8 the width of the riiile grooves will be narrowed, and the particles thrown in the grooves will be agitated. Repeated compression and expansion of the spring re-classii'les the particles collected in the grooves and perfects concentration.

In Fig. 3, a rotary bowl concentrator is shown which embodies the same principles of operation as that shown in Fig. l, the details of which are here explained for the purpose of illustration. This precise apparatus is shown andclaimed in my co-pending application led of even date herewith.

The concentrator shown in Fig. 3, consists of a housing Il, enclosing a rotary bowl, the top of the housing having a central opening and an upconcentration operation.

is poured at the beginning of and during the Stretched across the y opening in the hopper I2 isa screen I3, the openextension thereof is a conical hub cap 2| which ing registering with a funnel portion I4 extending into the bowl and discharging pulp thereto.

The bottom of the bowl is raised in the central portion and a stationary vertical support I5 extends upwardly beneath this portion of the bowl to provide a sleeve for the bowl axle I6. The bowl is mounted on the axle by means of nut I1 which engages washer I8 to hold down the bottom portion I9 of the bowl. The portion of the axle I5 which extends through the bottom I9 is conical `and is slotted as at.20 for a locking key. Covering the end of the axle and screwed to a threaded of the sleeve 22.` Packing 21, disposed within the ring 26, protects this portion of the'- axle. The ring has an annular depending flange 28 which fits into the upper end of sleeve 22 to position said ring and to retain the outer portion of the cage 23.

#The lower bearing cage 24 is retained by a nut 29 engaging a threaded portion at the end of the y axle, and a lock washer 30 engages a detent 3I in the end of the axle to lock the nut in position. A plate 32 enclosesl the lower end of the axle and is bolted to the sleeve'22, a gasket 32' being provided. to fseal the bearing.

For lubrication of the bearings, oil is pumped through a channel in the wall of the sleeve 22 to the top bearing and allowed to flow down between the axle and sleeve to the lower bearing and out through a central opening in the plate 32. An oil pump may be attached to the system for recirculation of the oil.

The structure just described is supported onV a base member 33 disposed beneath a horizontal flange 34 of lthe sleeve 22 and bolted thereto. 'I'he base member is part of a rectangular frame with longitudinal side rails and cross members disposed beneath the bowl and the motor, as shown in Fig. 4.

Returning now to the bowl, the bottom portion contains a number of passageways 35, provided with vanes for directing the pulp to the bottom of the rime chamber, the upper openings of the .passageways registering with the end of the funnel I4 in the top of the bowl. This bottom portion is also conical so that the pulp is forced outwardly as well as downwardly to the bottom of the riilie chamber. To protect the metal dening these passages from the lforce of the outwardly thrown ore, a lining 31 oi flexible material such as sand-blast rubber is applied to the outer walls of the passages.

The pulp which ows lout of the lower end of the passageways 36 enters the bottom of the rille chamber 38 and is forced outwardly and upwardly by centrifugal force to the top of the bowl. The

' bottom ofthe rille chamber is also protected by a lining 31', a number of thin, vertical vanes 39 holding the same in place and also cooperating with the ring 40 to secure the lower ends of the 2,161,477 wardly projecting hopper I2 intowhich the pulp rile sections. There are a number of openings in the bottom of the' bowlas at 4I through which the pulp may be flushed into a stationary circular trough 42 mounted on the flange 34. Trough 42 has an inclined bottom and a spout 43 at its lowest portion. When the bowl is rotated no pulp will flow through the openings 4I because of the centrifugal force, but when the riilles are lled and it is desired to clean out the bowl, rotation may be stopped and flushing fluid permitted to enter the rlflle chamber through one or more pipes 44 and the concentrates collected beneath the spout 43. Pipe 44 may be provided with holes 44', facing the rimes, through which the flushing uid may be sprayed. n

In order to rotate the bowl, there is an extension 45 on the bottom portion of the bowl which serves as a pulley and has slots for a number of V shaped driving belts 46. These belts are driven by a pulley 41 mountedon the vertical shaftof ,a motor 48 positioned at one side of the bowl.

The bowlis supported by a number of' rolls 4,9 mounted on the base, three such rolls being vshown in the present embodiment, spaced around the outer periphery of the bowl. Each roll contacts the bottom portion 5I) of the lateral wall 5I of the bowl, and is provided with a rim 52 outside th'e bowl, for retaining the side wall ofthe bowl.

Around the outer periphery of the bowl, but located within the wall 5I are a, number of vertical studs 53 and 54. Stud 53 shown yat the right side of the bowl in Fig. 3 is mounted directly-on the bottom of the bowl and held rigidly by anut engaging the threaded portion extending through the bottom wa1l-of the bowl. In the drawings 24 studs are shown, the number selected depending upon the size of the bowl and the support necessary for the riilie surface. -Stud 54 shown at the left side of the bowl is not rigidly mounted to the bottom of the bowl, but is free to move in axial direction with respect thereto. Alternate studs on the bowl are similarly mounted in the manner of studs 53 and 54 respectively, in'order that the desired vibration of the riilles may be obtained.

Located inside of the riille chamber is the riille sleeve-55, the contour of which has been carefully designed to aiford the maximum receptive volume for ore concentrates under efficient operating conditions. The upper wall of each riiile groove in the sleeve 55 is horizontal and from the base of the pocket or groove the other wall normally depends -inwardly at an angle of approximately 40. This contour affords optimum rifile surface and also permits reenforcement by spaced metallic members or plates, which impart vibratory motion to the riflles. f

It will be noted that the diameter of the riiile wall is smaller at the bottom of the bowl than at the top and to accomplish this the lower-rows of riilies are disposed further inwardly than the uppermost rows.

of supporting plates or rings, each of which would be of Adiffer-lent inside diameter.. A single offset, as shown in Fig. 3., requires only .two sizes of plates, and is less costly to construct.

the plates 56 are a series of annular plates 59 The rows might be tapered in a uniform line but that would necessitate the use mounted on the lateral wall 5| of the bowl, openings 60 being provided in plates 59 through which studs 53 extend. `There must be enough clearancefor the movement of the plates 59 relative to the studs to impart the full oscillatory-transverse vibration to which these plates maybe subjected. Plates 56 and 59 are continuous about the bowl periphery in the form of rings, plates 56 being rigid with respect to the bottom of the bowl, and plates 59 being rigid with respect to the side of the bowl. Plates 56 and 59 are provided with chamfered inner edges 6| which conform to the desired shape of rime sleeve. The inner ends of the plates contact the riflie sleeve and are to support the same as well as to control the contour of the riflies during vibrations. a

The mounting on studs 54 is similar in all respects to that just described on studs 53, except that the plates 59 are rigidly xed to studs 54, whereas relative to studs 53 axial and radial motion is permitted. Plates 56 will thus engage every other stud around the bowl, whileplates 59 will engage alternate studs not engaged by plates 56. In this manner the riflles willbe supported by two relatively movable sets of plates which are mounted respectively on alternate studs. x

Disposed beneath the bottom plate 59 on studs 54 and between the abutting surfaces of sleeve extension 58 and the bottom of the bowl and engaging studs 53 is an annular, formed springring 62, the purpose of which is to resiliently carry the studs 54, which are not rigidly mounted on the bottom of the bowl. From the method of mounting described it will be seen that the lateral wall of the bowl may be moved in a vertical and horizontal direction while the bottom portion remains fixed in its central bearing support. The spring-ring 62 is of a conventional sinuous form and its annular design serves to maintain `the floating studs 54 in propercircumferential position in relation to the bottom of .the bowl.

Above the lateral wall 5| of the bowl is an annular member 63, to which the topof the rubber rile sleeve 55 is attached. The member ,63 has an upwardly projecting flange 63', over which the riffle sleeve is drawn, thus providing a higher wall for the rime chamber. Attached tothe top of member 63 and extending over the end of the bowl wall is a horizontal annular plate 64 over which the pulp flows from the bowl. Plate 64 is bolted to member 63 at a number of points, the section of the plate lying on theinside of the bolts engaging the endsof the riflie sleeve to hold down the same. Studs 53, which ar'e rigidly mounted on the bottom lof the bowl, are also rigidly attached to member 63, there being a nut 65 engaging the upper end of each stud 53 above the member63. Studs 54 are not attached to member 63 and are free to move relative thereto, enough clearance being provided above the ends of suchstuds and below member 63 to permit such motion without interference. Connecting the top ends of all studs is a spring-ring 66, of similar design as spring-ring 62 which engages the lower "ends of the studs. Both spring-rings cooperate sid the bowl wall to provide a trough 68 for overflowing pulp. In order to protect the metal.

from particles thrown from the centrifuge the top of the housing and the upper portion of the side wall is lined with aj suitable lining such as sheets of sandblast rubber. The bottom 69 of the trough 68 is inclined and the pulp is permitted to ow downward in a spiral trough to the outlet 10 which is tangential to the bowl. The housing is mounted on the base in any suitable manner,

clearance being provided for the V-belt driving 'the centrifuge, and for easy access to the supporting rolls. It is preferable to make the housing detachable to permit access to the interior of the-bowl for inspection or repairs.

Each roll 49 is mounted -on a shaft 1|, provided with suitable bearings 12. The shaft 1| is supported on a bracket 13 mounted on the frame by means of bolts. Any of the rolls may be elevated by inserting shims 14 between the base of the bracket and the frame 33, but the particular manner of accomplishing this result is immaterial insofar as the scope of this invention is concerned. Forinstance, theshaft of the rolls might be mounted in a sleeve eccentric therewith, the rotation of which would elevate the center of the rolls.

When the pulp containing finely ground particles of different' specific gravity -but of fairly uniform size is poured into therotating centrifugal concentrator the heavier particles in the fluid will be thrown into the riilie grooves, where they will become imbedded. Along with the particles desired to `be classified, such as gold, will be particles of sand and the like which are not desired. In a bowl with non-vibratory riflies, particles will become packed in the riilie pockets and clog the same, thereby preventing further classification;

By the invention here disclosed, the walls of the riflle pockets may be contracted and expanded or the base of the groove may be moved inwardly to agitate particles deposited therein and permit improved concentration. When the walls of the riiiie are moved toward each other, there will be a pinching effect and a squeezing out of particles, with the heavier particles being retained at the apex of the riie grooves. Simultaneous with this effect, there will be an expansion of the walls of the adjoining riliies, which expansion will automatically deflect the rife base toward the bowl center, thereby loosening ore deposited in the groove and permitting more intensive agitation. The total volume of the riflie groove in the last vposition may be increased, but the depth is decreased, and as a result eddies are caused due to friction with the pulp stream. The pulp which is forced from the groove. will be sheared off by the upward flow of iiuid and forced into the next higher groove where centrifugal lforce will again operate to improve the concentration of heavier particles.

This desired agitation may -be controlled in the following manner. By elevating two of the rolls and dropping the .other roll, the plane defined by the contacting points on the three rolls will be inclined to the horizontal, thus imparting an axial, wabble vibration to the riiiie sleeve.' This inclination of the bowl cylinder will lift plates 59 mounted on the cylinder as they pass over the raised rolls, and then lower them to the other extreme position as they pass over the depressed roll. Meanwhile plates 56 remain in xed elevation because of their rigid attachment to the bottom of the bowl by the studs 53. The axis of the studs 53 and 54 will not be parallel in this position, but slightly inclined to each other because of the inclination of the axis of the side wall of the bowl, which carries studs 54, relative to the axis of the bottom of the bowl which carries studs 53. The free mounting of alternate stds, suoli as studs 54, in the manner described, enables the apparatus to assume these changing positions at high speeds of rotation without unduly stressing the members.

The centrifugal bowl structure shown in this application is claimed in my copending application 186,930, rlled January 26, 1938. \v The invention having been described what is claimed is: j

1. The method-fief concentrating ores which comprises passing-the pulpeontaining ore to be concentratedalong a surface composed of riilles arranged transverselyuto the ilow of pulp, periodically widening and'narrowing the grooves between the riflles and collecting the concentrates deposited in the grooves.

2. The method of :concentrating ores which comprises passing pulp containing ore to -be concentrated along a surface composed of a series of riles arranged' transversely of the direction of the pulp ow, reciprocating alternate rimes period'ically in the direction of thepulp flow while the remaining rimes are stationary with respect thereto, and collecting the concentrates deposited in the grooves between the riilles.

3. The method of concentrating ores which comprises passing pulp containing ore -to be concentrated along a surface composed of a series of riiiles arranged transversely of the direction of the pulp flow, narrowing alternate grooves between riilles periodically to expel a portion of the maar?? ore deposited in the groove, simultaneously widening the remaining grooves periodically to reclassify concentrates collected therein as well as concentrates expelled from adjoining riiile grooves, periodically narrowing the last named grooves while the first named grooves are widened, and collecting the concentrates finally deposited inthe grooves between the riiiles.

4...'Ihe method of concentrating ore's which comprises passing the pulp containing the ore to be concentrated over a surface composed of a series of rimes defining riiile grooves arranged i transversely of the pulp 110W, periodically reciplrocating the rimes in the direction of the pulp flow to widen and narrow the rime grooves and periodically reciprocating the bases of the riflle Agrooves transverse to the direction of the pulp ow, the latter reciprocation being so timed that the bottom of the rime groove defines a shallower out the ore deposited in the grooves.

ALFRED H. LEJ A. 

